Fourteenth International Conference on Climate Change: Impacts & Responses

Abstract

The temperature humidity index (THI) is one of the measures to describe heat stress, especially when animals’ production (meat and milk) is considered. It is expected that THI values will vary due to changes in temperature and humidity in the coming decades. The aim of this study is to investigate the effects of climate change on THI and milk production under Representative Concentration Pathway (RCP) climatic scenarios proposed in the fifth assessment report (AR5) of IPCC in the western region of Iran. The climatic projections required for calculation of THI values during the future period were obtained from EC-EARTH model outputs, downscaled and calibrated for the study region. The suitable equation for calculation of THI was based on the climatic condition of selected study stations. The index values for baseline and future period were calculated and the trend of variation was worked out. Besides, the number of days with different level of heat stress in annual and monthly basis under RCP4.5 and RCP 8.5 scenarios during four periods of 1981-2010, 2011-2040, 2041-2070 and 2071 to 2100 were calculated and compared with corresponding values of the baseline period. The results reveal that the index would be less affected by climate change during the months of April and May. The trend of milk production affected by climate change, during the future period is decreasing and significant at 99% level of confidence. Such that, by 2100, under RCP 4.5 and 8.5 scenarios, milk production would decrease 1 and 2 kg per year, respectively.